Fluid Turnover in Renal Cysts

Abstract

Cystic puncture was performed percutaneously in 18 patients with solitary renal cysts and in 22 with multiple, congenital renal cysts. With the aid of 3H-water it was possible to estimate the fluid turnover in the cysts and compare it with their volume, pressure and K and creatinine levels. Fluid turnover was rapid in all the renal cysts. After i.v. injection of 3H (2-5 h), the 3H concentration in cystic fluid averaged 88% of the concentration in plasma fluid in patients with polycystic kidneys and 73% in patients with solitary cysts. Fluid turnover was more rapid in small than in large cysts, but there was no such difference between cysts with high and low pressure. The fluid turnover was slightly faster in cysts with high K and creatinine levels than in those with low levels. The fluid turnover in a renal cyst of 10 ml was considerable, probably more than 100 ml/24 h. Fluid inflow to the cyst came mainly from cells in the cyst wall and not from a single glomerule. Fluid probably left and cyst actively via cells in the cyst wall, since the fluid turnover did not increase with high cyst pressure. The fluid turnover was probably secondary to the active solute transportation, which was performed by the cyst cells. These cells had a tubular cell-like function and should respond to pharmacotherapy.